Just ill-informed Congressmen sitting around one day saying to each other "Let's stir the pot" so they banned them.
You have to understand that the United States lighting requirement is met mostly through the widespread installation of fluorescent lighting systems ~ and that has been the case since the early 1950s.
Incandescent lights consume such a small part of the national power production they are and have been IRRELEVANT for a very long time.
Only by claiming that all incandescents were in an on state 24/7 were their analysts to come up with a projected savings of $21.33 per year for each person. Since most incandescents are actually NEVER ON most informed analysts suggest that the maximum feasible savings would be more like 1% of that, or less than a quarter dollar per year, and that assumed that you would purchase and use only the most efficient fluorescent lights possible. As it turns out in heavy use in the home fluorescent lights don't take well to being turned on and off all the time, nor do they stand up well to WET ENVIRONMENTS ~ when they are in close proximity to the "wet".
So any savings are probably ephemeral at best, and might even be LOSSES.
Congressmen are, when you get right down to it, innumerate.
Please explain.
It wouldn't matter if they WERE right for the first time ever on the merits...this issue is simply beyond their jurisdiction.